John is a lawyer living in New York who makes the impulsive decision to receive a genetic engineering injection that stops aging. Initially highly logical, he struggles to adapt to a society where human relationships and structures rapidly change. He carries deep-seated fears of losing his loved ones, driving a desire to convince his family to also undergo the procedure.

David is John and Sonia's son, born into a world adjusting to the postmortal cure. As he grows up, he develops into a muscular, talented basketball player who strongly resembles his father. Rejecting his father's isolation, David becomes a devout member of the Church of Man, a religion worshiping humanity and disavowing violence.

Alison is John's childhood classmate and first love from middle school. She is a naturally beautiful woman with brown hair who recently went through a divorce. Reconnecting with John as an adult, she brings out his passionate feelings.

Solara is a striking blonde woman who immediately captures John's attention. Her presence serves as an initial catalyst for John's decision to go through with the postmortal cure. She possesses superior athleticism and operates under multiple aliases to survive in an increasingly dangerous society.

Ernie is a muscular, bald man with a black goatee who works in end specialization. He is proficient with firearms and capable of reading dangerous situations to ensure survival. Despite the grim nature of his profession, Ernie maintains a lax attitude and views his work strictly as a means to provide for his wife and children.

Katy is John's roommate who exhibits great enthusiasm for life and the future. Eager to remain forever young, she convinces John to share his doctor's contact information in exchange for paying for cable. She resolves to make something meaningful out of her indefinite lifespan.

John's father is an older man who receives the postmortal cure despite being above the recommended age. He deeply mourns his late wife and openly expresses his displeasure with having taken the cure, longing for an afterlife where he might reunite with her.

Sonia is John's partner who desires the stability of marriage in a world where commitment is eroding. She craves traditional family structures and wishes for John to invest in a shared future, putting them at odds over how to handle their indefinite lifespans.

Polly is John's sister who chastises him for getting the cure out of concern for his well-being. She struggles with the implications of an unaging society on future generations and fears for the stability of her own marriage.

Matt is an entrepreneur who runs a private company assisting people in ending their lives. He handles the bureaucratic side of the business, submitting exit interviews to the Department of Containment and assigning tasks to his field workers.

Scott is a friend and roommate of John who embraces the celebratory culture surrounding the postmortal cure. He partakes in the new social norms of the unaging society, such as elaborate resort parties, and remains dismissive of alternative movements.

Chan is a former coworker who worked for John's firm during an expansion endeavor. After receiving the cure in America, he returns to China, where the procedure is illegal, and faces severe persecution from government officials enforcing strict anti-cure policies.

Nate is Sonia's fiancé who steps in to help raise her child. He embraces the traditional family life that Sonia desires and attends the Church of Man, though he is less devout than his stepson.

Mark is Polly's husband who wishes to convert their traditional union into a cycle marriage that expires after a set decade. His desire for a temporary commitment causes deep insecurity and strife within their family.

Randall is an anti-cure extremist dying of cancer who vehemently refuses the genetic treatment. He orchestrates bombings and violence against those who support the cure, viewing his terrorism as a necessary war to save humanity from the consequences of eternal life.

Julia is a sex worker who was cured at eighteen, leaving her with an eternally youthful appearance that causes people to dismiss or mistreat her. Having been expelled from a luxury island community due to her infertility, she carries deep fatigue regarding her unchanging existence.

Reverend Swanson is a leader within the Church of Man who works to reform end specialization. He holds strong anti-violence principles and seeks to convert rather than destroy his enemies, demanding that end specialists cease their work.

Ken is a collectivist from the Church of Man who provides support to John. He acts as a messenger for the church community, delivering difficult news while maintaining the religion's stoic, non-violent stance.

Reverend Jeffs is a leader who provides sanctuary to refugees. He maintains strict adherence to the church's doctrines, holding mixed feelings about outsiders who have committed violence while still offering them medical care and spiritual rites.

Known as Edgar The Swift, he is one of the wealthiest men in the United States and a famous rockstar. Living in an idyllic Maryland neighborhood protected by armed guards, he seeks to solidify his musical legacy by orchestrating his own demise.